1. Field of the Invention
This invention relates to a shutter.
It relates more specifically to a shutter of the type known as a "roller shutter" in which a shutter curtain made up of articulated laths is extended from a roller housing along a guide track, the shutter being extended by drive means, usually an electric motor.
2. Description of the Prior Art
Conventional shutter curtains used to cover an opening are withdrawn onto a roller having a generally horizontally disposed axis. In use, the shutter may be lowered in a more or less vertical direction from the roller to cover for example a shop window or door opening. Another form of shutter curtain is used as a fire barrier to cover an escalator and, in this case, it will be extended in a generally horizontal direction from the roller, which again has a horizontal axis.
However, difficulty arises when it is desired to cover for example a shop frontage having an irregular shape, perhaps including a curved portion or an inward recess or outwardly projecting window bay for example. At present, it is necessary to use a number of vertically opening shutters arranged edge to edge to approximate to the shape of such a frontage. Intermediate guide tracks need to be placed in vertical position to guide the edges of these discrete shutter curtains, separate drive means need to be provided for each shutter and the arrangement is expensive, clumsy and time consuming to operate.
Furthermore, there are limitations on the width of opening which can be covered by a single vertical shutter and substantial overhead clearance is required for the housing within which the shutter is rolled when not in use.